Hey guys/gals, well as promised I have been chasing down an answer to this violent 40 MPH deceleration wobble that many of us have experienced and I am passing along what BMW did to fix the wobble for me. I left my LT with Blue Moon Cycle BMW in Atlanta for 3 weeks while they tried different things to fix it. I applaud them for not simply blowing it off saying its the nature of the beast. After test riding it they agreed it was nothing like it should be.
My bike is now very smooth and again and I'm pretty happy. The decel shake is still there a little bit if I take my hands completely off of the bars or if I am barely touching them, but it's nothing like it was. Before I really had to hold the bars and hated how unstable and pronounced it felt on decel, it didn't feel normal, but now I can apply the smallest amount of pressure to keep things true and stable and I'm willing to settle with that. I realize that it is the nature of some big bikes to have this sensation, but in my experience this seemed rather extreme.
My 2006 LT and tires have about 8K miles on them and I'm running the Metz 880's. I suspect it would be even smoother with a new set of rubber, but again, this it once again really nice to ride, like when I first drove the LT new. Yeah I wish is were as smooth and nimble as my GS and that I could take my hands off, but it's not a GS. The LT is a big girl and demands a little respect and attention at times or she may turn on you and I'm all about giving it to her, and I'm okay with that.
Was it a complete fix? Mmmm maybe not as I wish it wasn't there at all, but it is tons better than it was and I no longer find it unsafe so I can deal with it like this. I don't ride the LT without my hands on the big girl often and since this feels resonable to me, I can live with it. I do wonder why a bike with such low mile would require this type of repair, but perhaps it's either due to the size/sensitivity of the bike or simply a bad batch of parts. It happens.
I am told that the key part they replaced that made the difference was the Lower Ball Joint, I think the part# is 31 42 7 681 040 for the new joint and 31 42 2 330 996 for the NUT.
They also replaced and tried other things before that such as the steering damper, rebalancing the tires, and other suspension related fixes, but these other attempts didn't help.
The work order says the cause of the worn lower Ball Joint going bad was the tire balance. I don't know if I really buy that or if was simply something they had to put in the order for warranty purpose. At any rate, everything was covered under warranty I'm happy to say.
For anyone with an LT experiencing what I considered to be an unreasonable and pronounced violent deceleration wobble, I hope that this helps you out. Again, Kudos to Blue Moon Cycle, I think they are the best dealer in Atlanta and I thank them for for sharing my concerns and finding an answer to my problem. Ride safely and ride often. ~darren